Apparatus for manufacturing composite casting of brake-disks

ABSTRACT

A method and apparatus for the manufacture of compound cast brake disks having a cast friction ring forming the brake disk, properly speaking, in which a steel hub provided with a centering aperture is centered on a rotatable centrifuging table by means of a centering pin or the like whereby the flange-like radially outwardly extending edge of the hub projects into the mold for the cast friction ring which during the rotation of the centrifuging table is filled with the melt from the outside toward the inside.

United States Patent 1191 Funke I APPARATUS F OR MANUFACTURING COMPOSITE CASTING OF BRAKE-DISKS [75] lnventor: Giinter Funke, Deufringen,

Germany [73] Assignee: Daimler-Benz Aktiengesellschaft [22] Filed: Mar. 29, 1972 21 Appl. No.; 239,042

I 30] Foreign Application Priority Data Mar. 30, 1971 Germany 2115299 [52] US. Cl. 164/288, 164/302 [51] Int. Cl B22d 13/04, 822d 19/00 [58] Field of Search 164/98, 111, 112, I14,

[56] References Cited UNITED STATES PATENTS Sargent... l64/288 X June 28, 1974 3,094,753 6/1963 Klement 164/288 x 3,430,681 3/1969 Smith et al 164/288 x Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney, Agent, or Firm-Craig and Antonelli [5 7 ABSTRACT A method and apparatus for the manufacture of compound cast brake disks having a cast friction ring forming the brake disk, properly speaking, in which a steel hub provided with a centering aperture is centered on a rotatable centrifuging table by means of a centering pin or the like whereby the flange-like radially outwardly extending edge of the hub projects into i the mold for the cast friction ring which during the rotation of the centrifuging table is filled with the melt from the outside toward the inside.

20 Claims, 6 Drawing Figures PATENTEBJUNZB'IW 3.820 588 sum 3 BF 3 FIG. 5

APPARATUS FOR MANUFACTURING COMPOSITE CASTING OF BRAKE-DISKS friction ring forms the brake-disk, properly speaking,

and which has a rectangular cross section.

However, in the sand-mold casting method, numerous preparations are necessary for the casting of each individual brake disk. The sand-mold casting method involves relatively high salary expenses and therefore is relatively expensive.

It is an aim of the present invention to avoid these disadvantages by'a casting method which permits to manufacture larger series of brake-disks in identical time intervals.

The brake disks should thereby be capable of being manuafactured easily with always the same quality and accuracy. The steel hub should not warp thereby and should be capable of being used in that condition, i.e., without further machining,'for the mounting or chucking during the finish-machining of the cast-on friction ring and during the final assembly at the vehicle.

The underlying problems are solved according to the present invention in that a preferably deep-drawn steel hub provided with a central aperture is centered by means of a centering pin of a rotatable centrifuging table, whereby the flange-like radially outwardly extend ing edge of the steel hub, constructed in particular of scalloped shape, projects into a mold for the cast friction ring by means of a centering pin of a centrifuging table; the melt is thereby introduced by the rotation of the centrifuging table'into the mold which isthereby filled with the melt from the outside toward the inside.

Furthermore, a core having a separating surface approximately at the height of the flange-like edge may be installed on the rotatable centrifuging table having a cavity or recess provided with the centering pin, into which the steel hub is inserted centered by this pin with the centering aperture facing downwardly; the melt is then poured onto thecore during the rotation of the centrifuging table.

Reversely, the hub with the centering aperture pointing upwardly may be so mounted centered on the centering pin projecting out of the mold, that the edge of the hub projects into the mold and the melt is poured onto this edge during the rotation of the centrifuging table.

For carrying out the method of the present invention, an apparatus may be used consisting of a centrifuging table and of a mold, in which the table has recesses having a smaller depth than the cavity but a larger diameter than the latter and disposed concentric thereto, into which are adapted to be inserted ring-shaped mold parts surrounding the edge and forming the mold, which surround the friction surface and the outer end face of the friction ring during the casting operation.

The ring-shaped parts of the mold, which surround the friction surfaces as well as the outer end face of the brake disk during the casting operation, may be constructed angularly shaped in cross section. However, a disk-ring-shaped mold part and a ring-shaped mold part of angularly shaped cross section may also be so placed into the recess that the peripheral zone of the disc ringshaped mold part constitutes the support for the bent portion of the upper ring-shaped mold part of angularly shaped cross section. A cylindrical core fitting into the hub may thereby be inserted into the hub; the upper surface of the core is thereby flush with the upper surface of the hub.

However, the mold inserted into the centrifuging table may also consist of two ring-shaped mold parts of angularly shaped cross section. These mold parts may be so placed into recesses that the angularly bent portions of these mold parts are directed toward one another and enclose a disk-shaped core provided with radial slots, whose one surface abuts at the outer surface of the edge of the hub. The notches or grooves between the scallop-like projecting portions of the edge of the steel hub may be provided at the same place as the slots. The deep-drawn steel hub may also be secured at the centrifuging table for the purpose of avoiding floating during the casting.

Accordingly, it is an object of the present invention to provide a method and apparatus for the manufacture of compound cast brake disks for vehicles which avoid by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a method and apparatus for the manufacture of compound cast brake disks which permits a relatively economic manufacture without requiring complicated and numerous preparations.

A further object of the present invention resides in a method and apparatus for producing cast brake disks by centrifugal casting, which assure a product of always equal quality and accuracy in its dimensions, thus avoiding costly and time-consuming finishing operations thereof.

These and further objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIG. 1 is a cross-sectional view through a centrifuging table in accordance with the present invention into the cavity of which is inserted a hub with a downwardly directed centering aperture, with a cylindrical core inserted into the hub and with mold parts of disk-shaped and angularly shaped cross section inserted into a recess of the centrifugingtable;

FIG. 2 is a cross-sectional view through a modified embodiment of a centrifuging table in accordance with the present invention with a hub inserted in a similar manner into a cavity thereof and with mold parts of angularly shaped cross section inserted into recesses of the centrifuging table, which enclose between the angularly bent portions a disk-shaped core;

FIG. 3 is a cross-sectional view through another centrifuging table in accordance with the present invention on which is placed a hub provided with its centering aperture directed upwardly, and with mold parts of angularly shaped cross section inserted into recesses which enclose therebetween a disk-shaped core between the angularly bent portions thereof;

FIG. 4 is a cross-sectional view through a modified embodiment of a centrifuging table in accordance with the present invention onto which a hub is mounted in the same manner as in FIG. 3, and with mold parts of disk-shaped and angularly shaped cross section inserted into a recess of the centrifuging table;

FIG. is a cross-sectional view through a still further modified embodiment of a centrifuging table in accordance with the present invention with a hub provided with its centering aperture directed upwardly which, rests centered on a mold part which in turn rests centered on a further mold part into which a core is inserted; and

FIG. 6 is a cross-sectional view through a still further modified embodiment of a centrifuging table in accordance with the present invention with a hub provided with its centering aperture directed upwardly which is secured centered at a mold part that in turn rests centered on a further mold part.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, and more particularly to FIG. 1, reference numeral 1 designates in this figure a centrifuging table of otherwise conventional construction which is adapted to be rotated by conventional means, not illustrated for the sake of simplicity. A compound cast brake disk is to be manufactured by means of the centrifuging table 1, whose friction ring 2 of cylindrical ring-shape and representing the brake disk, properly speaking, is cast. The centrifuging table 1 has in the center a cylindrical recess or cavity 3 into which a steel hub 4 deep-drawn without cutting operations into finished size on a multiple-die press is so inserted centered that its centering aperture is directed downwardly. The centering is achieved by a centering pin 5 on which is mounted the finished steel hub 4 with its centering aperture 10. A recess 6 accommodates the mold parts. The latter consists, on the one hand, of a disk-ringshaped mold part 7 which is placed on the bottom of the recess 6 and which, as to the rest, fits into the recess 6 with respect to its diameter. A ring-shaped mold part 8 of angularly shaped cross section is so placed with its angularly bent portion 9 on the disk-ring-shaped mold part 7 that the angularly bent portion 9, which, as to the rest, is matched to the diameter of the recess 6, rests on the peripheral zone of the disk-ring-shaped mold part 7. A cylindrical core 11 fitting into the hub 4 is now inserted into the latter. The core 11 is just so high that its thickness corresponds to the distance from the upper edge of the centering pin 5 to the upper edge of the steel hub 4 inserted into the mold so that the upper surface i2 of the core 11 is flush with the upper surface 13 of the steel hub 4.

The mold parts 7 and 8 thus form the mold, properly speaking, for the cast friction ring 2 and surround the same at its two friction surfaces 15 and 16 as well as at its outer end face 17. A flange-like radially extending edge 18 which now projects into the mold constituted by the two mold parts 7 and 8, is welded together with the cast friction ring 2 during the casting of the cast friction ring. In order to achieve a connection between the cast friction ring 2 and the edge 18 of the hub 4 which cannot become loose, the edge 18 is constructed around its periphery scallop-shaped, i.e., with cuts 19 forming teeth. The cast friction ring 2 is therefore form-locking centrifuged onto the edge 18 of the hub 4.

For purposes of casting, the melt is poured onto the core 11 after the centrifuging table 1 has been set into rotation. The mold constituted by the mold parts 7 and 8 is filled completely. After its filling, excess melt and the contaminations thereof by oxides and the like flow off along the inclined overflow edge 21 of the upper mold part 8 and thus simultaneously indicates the end of the casting operation.

So-called vented brake disks can be cast by means of the apparatus illustrated in FIG. 2, whose cast friction ring 14 is provided with radially arranged apertures 28. Also in this case, the steel hub 4 is inserted into the cavity 3 of the centrifuging table 1 with a downwardly directed centering aperture 10, the hub 4 is thereby centered by the centering pin 5. A ring-shaped mold part 22 of angularly shaped cross section is so inserted into the recess 6 that its shorter leg portion 23 projects upwardly. This shorter leg portion 23 is so long that its surface 24 is flush with the upper surface 25 of the flange-like edge 18 of the hub 4. A disk-shaped core 26 is now placed on the surfaces 24 and 25. This core 26 is provided with radial cuts or grooves 28 which extend from the flange-like edge 18 of the steel hub up 4 up to the periphery of the cast ring. A ring-shaped mold part 27 of angularly shaped cross section is now again placed on the core 26 with its shorter leg portion 29 directed downwardly. The outer diameter of the angularly shaped mold part 27 is slightly larger than the diameter of the ring-shaped mold part 22, and more particularly is so large that the angularly shaped mold part 27 fits into the recess 6.

For the manufacture of a vented compound cast brake disk, melt is now poured onto the disk-shaped core 26 after the centrifuging table 1 illustrated in FIG. 2 has been set into rotation by conventional means. The melt which after solidification forms the friction ring 14, then fills the space surrounded by the ringshaped mold parts 22 and 27 of angularly shaped cross section to such an extent until the melt can flow off by way of the inclined overflow edge 21. The melt can thereby also penetrate into the space surrounded by the ring-shaped mold part 22 through the radial cuts 28 provided in the core 26.

The cast friction ring, however, can also be cast onto the hub 4 if the deep-drawn hub 4 is so placed on the centrifuging table 31 that its centering aperture 10 is directed upwardly as illustrated in FIGS. 3 and 4. The centrifuging table 31 suited for this type of manufacture of compound cast disks does not have a cavity as with the centrifuging tables according to FIGS. 1 and 2 but instead includes an upwardly directed projection 32 of corresponding height at which is disposed the centering pin 5. For the embodiment according to FIG. 3, a core 26 is required, similar as in the embodiment described in connection with FIG. 2. In the embodiment according to FIG. 4, no core at all will be needed anymore.

In contrast to the embodiments described in connection with FIGS. 1 and 2, in which the melt was poured onto the surfaces of the cores 11 or 26, the melt has to be poured in that case exclusively onto the edge 18.

In order to avoid a floating caused by the buoyancy in the liquid metal, the hubs 4 are secured at the centrifuging table, for example, by means of screws or bolts.

- Furthermore, care must be taken during the installation of the cores 26 according to FIGS. 2 and 3 that the slots or notches 28 in the cores 26 come to rest on the cuts 19. The number of the slots 28 as well as those of the cuts 19 and theircircumferential distribution must therefore always be equal.

FIGS. 5 and 6 illustrate further modifications for the manufacture of compound cast brake disks according to the present invention. The steel hub 4 is also arranged in these two embodiments with its centering aperture 10 directed upwardly. The hub 4 thereby abuts at a mold part 29 whose centering pin 32 provided with a melt inlet aperture 31 engages into the centering aperture 10 from above.

The base portion 33 of the mold part 29 has a step 34.-By means of this step or shoulder 34, the mold part 29 rests centered on a further mold part 35 which is secured in any conventional manner on the centrifuging table (not shown in this embodiment and of any conventional construction). The mold parts 29 and 35 surround the cast friction ring 2 (FIG. 6) and 14a (FIG. 5). The mold part 29 has again an inclined overflow edge 36 by way of which the excess melt and the contaminations thereof by oxides and the like can flow off after the filling of the mold with a melt that forms after solidification thereof the cast friction ring 2 and 14a; the melt thereby leaves through the windows 37 provided 'circumferentially in the mold part 29. If a vented brake disk with radial slots 28 is to be cast,

then an I-shaped core 38 with a central aperture 40 (FIG. 5) which is determined in cross section by the ring-shaped friction ring- 2 or 14a, is inserted into the mold, i.e., initially therefore into the mold part 35. The upwardly angularly bent edge 39 of this core 38 surrounds the inner wall surface 41 of the cylindrical wall '42 of the hub 4. The edge 39 of the core 38 can be used The centrifugal casting method offers considerable technical advantages compared to the sand-mold casting method. These advantages consist, on the one hand, in that, as a result of the solidification of the melt rotationally symmetrically from the outside toward the inside, the hub flange remains plane and flat, i.e., without distortion or warping. It may therefore serve without after-finishing as starting andabutment surface for the finishing operations of the friction surfaces of the friction rings 2 and 14.

On the other hand, a homogeneous cast structure devoid of shrinkage or piping is assured by the centrifugal casting method so that an X-ray examination can be dispensed with. Furthermore, during the casting the cuts 19 are circumcirculated along the entire circumference uniformly and with the same temperature so finish-ground. The inner diameter of the friction ring 2 disposed concentrically to the axis of rotation results automatically by the overflow edge25 with sufficient accuracy so that the inner surface of the cast friction ring 2 facing the axis need no longer be machined. The

ring can also be readily removed since its inner diameter does not abut anywhere so that any shrinkage is without significance.

With the vented brake disk according to FIG. 2, an accurate plane parallelism between the hub abutment surface and the air channel plane constituted by the radial cuts 28 results from the centrifugal casting method. The machining of the finished hub abutment surfaces therefore becomes easier which in turn has as a consequence a decrease of the number of products to be declared as rejects by reason of failures in the disk thickness.

However, the centrifugal casting method not only offers technical advantages but also economic advantages. For example, investments for conveyor installations, sand-mold preparation installations, castcleaning installations and molding machines are economized. The finishing installations require smaller amounts of space and fewer work forces which additionally are freed from heavy, dirty work so that extra heavy-duty pay can be eliminated. Furthermore, some machining stations up to the finishing operations areeconomized and finally the disk manufacture according to the centrifugal casting method can be far-reachingly automated. Finally, the casting can be machined immediately after solidification without having to remove the sprue or feeder and the riser.

While I have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto but issusceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What I claim is:

1. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on saidcentrifuging table means, a first and second mold means for holding said hub and cast friction ring, said steel hub having a flange-like radially extending edge portion projecting between said first and second mold means, said first and second mold means being supported on said centrifuging table means and substantially surroundingthe cast friction ring.

2. An apparatus according to claim 1, characterized in that said steel hub is a deep-drawn hub.

3. An apparatus according to claim 1, characterized in that said edge is provided with tooth-like means along the periphery thereof.

4. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, said centrifuging table means being provided with a centering pin disposed in a cavity of said centrifuging table means, said steel hub being inserted centered by said pin with its centering aperture facing downwardly, and a core inserted into said cavity and having a separating surface which, in its height, is approximately at the height of the flange-like edge of said hub.

5. An apparatus according to claim 1, characterized in that said centrifuging table means includes a centering pin projecting out of the mold means, the hub being so placed centered on said centering pin with the centering aperture thereof facing upwardly that the edge of the hub projects into the mold means.

6. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, said hub with its centering aperture being arranged facing upwardly abuts at a first mold part having a centering pin and provided with an inlet aperture for the melt, said first mold part engaging with its centering pin from above into the centering aperture of said hub and having a ring-shaped base portion resting centered on further mold part which, together with the base portion, constitutes the mold means for the cast friction ring.

7. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, a first and second mold means being supported on said centrifuging table means for holding said hub and the cast friction ring, said centrifuging table means being provided with a recess which is concentric to a cavity of said centrifuging table means, ring-shaped mold parts forming part of the mold means and surrounding the friction surfaces and the outer end face of the friction ring during the casting, being adapted to be inserted into said recess.

8. An apparatus according to claim7, characterized in that the recess has a lesser depth than the cavity but a larger diameter than the cavity.

9. An apparatus according to claim 8, characterized in that at least a portion of the ring-shaped mold parts which surround the friction surfaces as well as the outer end face of the friction ring during the casting are constructed angularly shaped in cross section.

10. An apparatus according to claim 7, characterized in that a disk-ring-shaped mold part and a ring-shaped mold part of angularly shaped cross section forming part of the mold means are so inserted into the recess that the peripheral zone of the disk-ring-shaped mold part forms the support for the bent-off portion of the upper ring-shaped mold part of angularly shaped cross section.

11. An apparatus according to claim 10, characterized in that a cylindrical core is inserted into the hub substantially fitting in the latter, the upper surface of the core forming the separating surface being substantially flush with the upper surface of the hub.

12. An apparatus according to claim 7, characterized in that two ring-shaped mold parts of angularly shaped cross section are so inserted into the recess that the angularly bent portion of these mold parts are directed toward one another and enclose a disk-shaped core provided with radial slots, whose one surface substantially abuts at the other surface of the edge of the hub.

13. An apparatus according to claim 12, characterized in that a core substantially l-shaped in cross section and having a central aperture is inserted into the mold means surrounding the cast friction ring, said core having an upwardly angularly bent edge which centeringly surrounds a cylindrical inner wall surface of the hub.

- 14. An apparatus according to claim 13, characterized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.

15. An apparatus according to claim 14, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting.

16. An apparatus according to claim 11, character ized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.

17. An apparatus according to claim 12, characterized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.

18. An apparatus according to claim 7, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting.

19. An apparatus for the manufacture of compound cast brake disks with a friction ring fonning the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, a core substantially l-shaped in cross section and having a central aperture is inserted into said mold means surrounding said cast friction ring, said core having an upwardly angularly bent edge which centeringly surrounds a cylindrical inner wall surface of said hub.

20. An apparatus according to claim 1, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting. 

1. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, a first and second mold means for holding said hub and cast friction ring, said steel hub having a flange-like radially extending edge portion projecting between said first and second mold means, said first and second mold means being supported on said centrifuging table means and substantially surrounding the cast friction ring.
 2. An apparatus according to claim 1, characterized in that said steel hub is a deep-drawn hub.
 3. An apparatus according to claim 1, characterized in that said edge is provided with tooth-like means along the periphery thereof.
 4. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, said centrifuging table means being provided with a centering pin disposed in a cavity of said centrifuging table means, said steel hub being inserted centered by said pin with its centering aperture facing downwardly, and a core inserted into said cavity and having a separating surface which, in its height, is approximately at the height of the flange-like edge of said hub.
 5. An apparatus according to claim 1, characterized in that said centrifuging table means includes a centering pin projecting out of the mold means, the hub being so placed centered on said centering pin with the centering aperture thereof facing upwardly that the edge of the hub projects into the mold means.
 6. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, said hub with its centering aperture being arranged facing upwardly abuts at a first mold part having a centering pin and provided with an inlet aperture for the melt, said first mold part engaging with its centering pin from above into the centering aperture of said hub and having a ring-shaped base portion resting centered on further mold part which, together with the base portion, constitutes the mold means for the cast friction ring.
 7. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, a first and second mold means being supported On said centrifuging table means for holding said hub and the cast friction ring, said centrifuging table means being provided with a recess which is concentric to a cavity of said centrifuging table means, ring-shaped mold parts forming part of the mold means and surrounding the friction surfaces and the outer end face of the friction ring during the casting, being adapted to be inserted into said recess.
 8. An apparatus according to claim 7, characterized in that the recess has a lesser depth than the cavity but a larger diameter than the cavity.
 9. An apparatus according to claim 8, characterized in that at least a portion of the ring-shaped mold parts which surround the friction surfaces as well as the outer end face of the friction ring during the casting are constructed angularly shaped in cross section.
 10. An apparatus according to claim 7, characterized in that a disk-ring-shaped mold part and a ring-shaped mold part of angularly shaped cross section forming part of the mold means are so inserted into the recess that the peripheral zone of the disk-ring-shaped mold part forms the support for the bent-off portion of the upper ring-shaped mold part of angularly shaped cross section.
 11. An apparatus according to claim 10, characterized in that a cylindrical core is inserted into the hub substantially fitting in the latter, the upper surface of the core forming the separating surface being substantially flush with the upper surface of the hub.
 12. An apparatus according to claim 7, characterized in that two ring-shaped mold parts of angularly shaped cross section are so inserted into the recess that the angularly bent portion of these mold parts are directed toward one another and enclose a disk-shaped core provided with radial slots, whose one surface substantially abuts at the other surface of the edge of the hub.
 13. An apparatus according to claim 12, characterized in that a core substantially I-shaped in cross section and having a central aperture is inserted into the mold means surrounding the cast friction ring, said core having an upwardly angularly bent edge which centeringly surrounds a cylindrical inner wall surface of the hub.
 14. An apparatus according to claim 13, characterized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.
 15. An apparatus according to claim 14, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting.
 16. An apparatus according to claim 11, characterized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.
 17. An apparatus according to claim 12, characterized in that the cuts between tooth-like raised portions of the edge of the hub are provided, respectively, at the same places as slots in the core.
 18. An apparatus according to claim 7, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting.
 19. An apparatus for the manufacture of compound cast brake disks with a friction ring forming the brake disk, properly speaking, comprising: a centrifuging table means, means for centering a steel hub provided with a centering aperture on said centrifuging table means, said steel hub having a flange-like radially extending edge portion projecting into a mold means for the cast friction ring, said mold means being supported on said centrifuging table means, a core substantially I-shaped in cross section and having a central aperture is inserted into said mold means surrounding said cast friction ring, said core having an upwardly angularly bent edge which centeringly surrounds a cylindrical inner wall surface of said hub.
 20. An apparatus according to claim 1, characterized in that the hub is secured at the centrifuging table means to avoid floating during the casting. 